Meeting deadlines at work and at home can stress you and increase the risk of heart attack while summer vacation eases down stress.
Climate and stress levels influence the risk of heart attack or myocardial infarction (MI). Time periods by calendar related to perceived stress are associated with the incidence rate of myocardial infarction (MI), says a new nationwide registry study of 156 000 people of the Swedish population, in the database SWEDEHEART.
‘Incidence rates of MI were higher on Mondays and during winter while it was lower in weekends and during the vacation month of July.’
Compared to control days, the daily incidence rate of MI was higher during the winter holidays, and on Mondays, whereas rates were lower during weekends and during the summer vacation in July. These periods coincide well with perceived high and low stress in society, respectively. The researchers used novel high-quality data from all Swedish hospitals on over 156,000 MIs registered during eight years (2006-2013) in the national quality registry SWEDEHEART.
This is the first study that investigates these culturally defined time-periods in the Swedish population with unselected, high-quality data. Previous studies have often lacked symptom start and discussed their results in terms of a delay in seeking appropriate care or delay of registration as explanatory for the MI rate variation over time. Other factors, such as temperature, also seem to have a limited influence on the MI rate changes.
Psychosocial demands on behaviour influences basal biological systems, even to such an extent that they may be potential triggers for MI. When controlling for national data on temperature, air pollution, and abroad travelling by air, the associations of calendar periods with MI rates are surprisingly robust.
“We have to remember that this is an observational study and be cautious with our conclusions. The systematic variation in MI rates is likely multifactorial. With that said, it is now more probable that stress explains a substantial portion of the fluctuation over time in population MI rates than it was before our study," says John Wallert.
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"To scrap the work-week routine would probably be way too drastic, says Wallert. How we in society have agreed on periods of work and rest is actually quite well aligned with our predisposed, internal biological clock, the circadian rhythm. However, the alignment is not perfect. For instance, our internal clock is highly unlikely to be aware if today is a Monday or a Sunday. An interesting sub finding was that out of eight subgroups, the group that was still employed had the greatest increase in MI rates of all, about 20% compared to control days. This and other findings might have a bearing on future public health and clinical policy," says John Wallert.
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